Definition of "Irregular" :
noun: merchandise that has imperfections; usually sold at a reduced price without the brand name
noun: a member of an irregular armed force that fights a stronger force by sabotage and harassment
adjective: not occurring at a regular rate or fixed intervals
"An irregular heartbeat."
adjective: independent in behavior or thought
"She led a somewhat irregular private life."
adjective: (of a surface or shape); not level or flat or symmetrical
"Walking was difficult on the irregular cobblestoned surface."
adjective: lacking continuity or regularity
"An irregular worker."
adjective: deviating from normal expectations; somewhat odd, strange, or abnormal
"Highly irregular behavior."
adjective: failing to meet a standard of manufacture due to an imperfection
"An irregular pair of jeans."
adjective: contrary to rule or accepted order or general practice
"Irregular hiring practices."
adjective: (of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
adjective: (used of the military) not belonging to or engaged in by regular army forces